Method of making shoes employing heat



June 14, 1960 M. s. BROMFIELD 2,940,096

METHOD oF MAKING SHOES EMPLOYINGHEAT Filed June 25, 1957 FIG. 2

2O 22 INVENTOR.

MORTON S. BROMFIELD GEORGE l.. GREENFi ELD ATTORNEY United States Patent mTHOD F MAKING SHOES EMPLOYING HEAT Morton S. Bromield, 8 HubbardiSt., Canton, Mass.

Filed June 25, 1957, Ser. No. 667,983

3 Claims. (Cl. 12-142) This invention relates to the art of shoemaking and more particularly comprises a new and improved method of attaching a sole to an upper. My invention, although applicable to the manufacture of all types of shoes having cemented soles, is particularly beneficial when practiced in the manufacture of shoes having high shanks.

The method of manufacturing shoes invented by ap Vactual time required for the cement to set is determined by the particular material from which the upper is made. While cement applied to a leather upper may require approximately two hours to set up, setting of the same jkind of cement on a vinyl upper may require twelve hours or more.

After the cement has set on the upper, the sole, which previously has received a coating of cement, is put in ,an oven to heat activate its coating. Although the application of heat is the most common method of activating the cement, it is also common practice to expose the sole to water vapor or apply the solvent of the cement to the coating to accomplish the same purpose.- Next, the sole is applied to the upper and the shoe is put in a press for ten to thirty seconds to aid in the formation of a proper bond between the sole and upper. It is particularly dicult to attach soles to high shank shoes because the sole must be made to conform to the irregular contour of the arch which prestresses the bond between the upper and sole.

There are a number of disadvantages associated with the conventional method of shoe manufacture described in the preceding paragraphs. One important disadvantage incident to the conventional process is that following the removal of the shoe from the press, it is possible to peel the sole from the upper because approximately twenty-four hours are required after the shoe has been removed from the press for the cement to attain maximum strength. During this long time interval, if less than the proper amount of cement has been applied, or if insuicient set-up time before sole laying has been allowed, or insufficient activation of sole cement has taken place, the sole may work away from the upper requiring disassembling of the shoe; worse still, if the separation is unnoticed, the ultimate wearing of the shoe will cause the weakly bonded sole to separate.

Another disadvantage resulting from the use of the conventional method is that the sequence of steps do not lend themselves to automation. As has been suggested, shoes made of dierent materials cannot be treated uni- 'formly for each material requires special handling. For .-example, while only two hours may be required for tial setting or hardening.

2,940,096 Patented June 14, 1960 ice cement to set on a leather upper, twelve hours may be required for the cement to set Von an upper made of vinyl. Furthermore, the time required for drying of the upper is determined by the particular material used in the construction of the upper.

Another disadvantage resulting from the practice of the conventional process is that a tremendously large number of lasts are essential in even a small shoe manufacturing operation. It is common knowledge that the cost of lasts represents the largest indirect cost in shoe making and more money is invested in lasts than in any capital equipment items, buildings, machinery or other property incident to the manufacture of shoes. Problems are also created in the conventional process by the application to the upper of non-uniform or excessively thick layers of cement because the setting of the cement will not be uniform from shoe to shoe or within various areas of a given shoe.

The primary object of my invention is to eliminate the many disadvantages enumerated above which are incident to the manufacture of shoes and, particularly, high shank shoes.

This and other objects of my invention will be better understood and appreciated from the following detailed description, read in connection with the accompanying drawings, in which:

Figures l-6 are fragmentary views illustrating the various steps in the sole laying operation practiced in accordance with my invention.

In the practice of my invention, the shoe upper 10 is assembled on the last 12 in the customary manner. That is, the upper is spread over the last and its periphery or bottom 14 is either tacked or cemented (not shown) to the insole 16 which has previously been secured to the last. Thereafter, as customary, the overlasted margin 14 of the upper is roughed by a wire brush to prepare it for the application of a coating .of cement and the steel shank (not shown) is stapled or secured by other means to the insole.

The rst step in my method, which constitutes a radical departure from the prior art, is the preheating of the overlasted margin of the upper 14 before any cement is applied to the bottom or periphery. This preheating `may be done in an infra red oven having a temperature of approximately 250 F. to,300 F. for about two minutes. A high shank lasted upper heated in that manner will have approximatertemperatu'res of 200 F. at the ball, 155 F. at -the shank, 155 F. at the forepart and F. at the toe. It is to be understood that any type of heat source can be used and the intensity of the heat in the oven will determine the duration necessary to heat the shoe to the approximate temperatures set forth above. This application of heat develops a heat reservoir in the overlasted margin of the upper for purposes which will become clear below.

After preheating, the overlasted margin of the upper is coated with cement 18 as suggested in Figure 2, which may be of any of the standard varieties now commonly used; for example, thermoplastic adhesives such as Hycar cement, neoprene, reclaimed rubber cement and animal and vegetable glues. After the cement 18` has been coated on the periphery of the upper, additional heat is directed to the exposed surface of the cement as suggested in Figure 3. This additional heat cooperates with the heat reservoir to condition the cement by evaporating the solvent in the cement and causing par- The reheat oven used to supply the additional heat may alsor have an infra red heat` source and its temperature maybe approximately 225 F. to 240 F. A11V overlasted kupper 'subjected to additional heat in such an oven for? approximately two t s 3 Y 'minutes'v willhave approximate temperatures of 200V F. at the ball, 180 F; at the shank, 165 F. at the fore part Y and 145"V F. at the toe. After the exposed surface of the setting of the cement on vthe upper in the practice of my method whereas from two hours to overnight is required for complete setting of the cement in the conventional process. Undoubtedly thisV great time saving is at least 5 in part achieved by the directV application of heat to both the lower and upper surfaces of the cement coating on the upper. The preheated overlastedY margin radiates its heat to the underside of the coating while the external heat from the reheat oven is applied to. its outerV surface.

Thus, the solvent evaporation is greatly accelerated`befwhensubjeeted to the given'oven temperatures for about Vtwo minutes. Thesvariations in temperatures over the "bottom,Y of the'shoe weregcaused by the irregularity of the bottomY surface.y Because of their :irregular nature, "theY various portionso'f the bottomsl did notlie at equal Ydistances( from the Yheat source. lAlthough the oven temperatures and heating times set forth above appear to be optimum, the desired resultswill be accomplished just Y so long( as theoverlasted margin of the upper 14 is Y1` reheated and yreheatedY to minimum temperaturesV of 120 F. and 130 F. respectively. VMaximum shoetemperatu'res are only limited by the amount of heat which will scorch kthe overlasted upper. It should also be noted 'that theVv temperature requirements in my process may be Vvariedby preheating the cement before it is Vapplied to the`v upper or by varyingthe solid to solvent ratio of the cement or glue.

t a After the upper jll) has been 4heated in the foregoing Vmanner, it is only necessaryvto activateV either the ce- ,ment'previously applied to thesole or the cement 18 on the Yupper before positioning the sole on the upper. In 'Figure 5 1 have illustrated a sole 20 having a coating :of

cement Y272 applied to one surface Ythereof and the soleYV Viis'juxtaposed Vto the upper 10. The cementon eitherV 'the sole 20 Vor the upper' 10 may be activated in a num 'ber of WaysV such as by heating, exposing to water vapor for applying arsolvent. Because the cement 18 applied ftothe upper passes through a tacky or active state Vv'after itV is removed from the reheatoven and before'it 16 upper and the laying of the sole.

fore the cement surface in contact with the -air formsjthe usual glaze film that greatly inhibits lthe solvent evaporation. It should be noted particularly that only four minutes elapse betweenthe `application of the cement to the My invention also eliminates the need for careful control of the thickness of the cement coating deposited. The greatly accelerated cement set-up in my process treats the irregularly/deposited heavy coatings. Further- 0 more, my process, in driving ot the moisture which is present to a lesser or greater amount in the pores of a `leather upper, depending on material, factory humidity 4and pretreatment, provides a uniformly dry surface which can properly absorb the cement. Thus, my proc- 5 es s insures'uniformly maximum bond strength with the body of the upper material. The tremendous time sav- Ying features of my invention also result in a substantial reduction of overhead in YtheV manufacture of shoes. While in the Vmanufacture of high shank shoes under con- .ventional methods `approximately one day is required Afor Y 'shoes to complete the manufacturing making cycle, the

o an upper made of such material it is possible to apply hardensr, with proper controlofthe cooling it is possible v Y.

`tov apply ,the sole 2 0 tothe upper 10 Without're-activating ithe cement" on either Vthe sole or the upper. Regardless Y .fof the manner in whichV thef'cement on either the upper Y j 'for .the'rjsole is Vactivated, theV next step is to coalign, the

'sole'vZQ vandfthe upper v10'and thereafter insert the upper Y Vffytitlr'the sole infra press(not shown).V The shoe may be' removed from the press after approximately tive to fifteen fseconds as `in the conventional method nowV practiced fin'the art. However, While the shoe is in'thepress this very shortrtime, the cementrachieves much of its maxirnum strength'and any attempt to peel the sole from the upper shortly after 'the shoeV is removed from the press will usually'result in tearing of the upper or sole. In

. Figure 6 Ijhave illustrated a portion ofthe completed 'shoe with the sole 20 secured to the bottom of the upper.

From the foregoing description, those skilled in the art will appreciate that the disadvantages of the Vcon- `ventional method alluded to above are overcome by `practicing myV new method. As'indicated,.the cement acquires substantially maximum strength shortly after Vattachmentpof thersole. Moreover, a heat balance is ,achieved for all shoe materials in that no special atten- V"tion must v,be given to the particular material used inthe :upperfgr the sole. The qtimes and temperatures given Y soles.VV Thus,l uniformity-of (operation kis achieved and 50 'vention be determined by the above apply equally to all materials such Vas leather, linen, reptilezand vinyl uppers and leather, rubber and plastic the previously cement coated Vsole to the upper imvmediately after preheating and without the application V-of a coating of cement tothe bottom 4ot' the upper forV the -preheating conditions the upper to receive the sole 5, :and may activate the cement on Vthe sole. Thus the preheatingfin certain instances may eliminate theV necessity forV applying a Ycoating fof cement to the upper. The advantages of'this method are obvious. The expensive vand time consuming operations of applying the cement "to 'the periphery of the upper Vand the cleaning of the upper after attaching the soleV are eliminated. Furthermore, there is no cement on the upper which could Vadversely aect its finish. Y Y

From the foregoing description :those skilled in the art will Yappreciate that numerous VVmodifications may be rmade of my invention without departing from its spirit. Therefore, I do not intend toV limit the breadth of invention to the details of the method described above but rather it is my intention that the scope of my inappended claims and their equivalents. Por example, although the specification Yrefers to preheating andrreheating of the upper, it is only necessary that this heat be applied to the particular 5 portion ofthe upper to which the cement is to be applied. 5- What I'claim Vas new and desire to secure by Letters Patent of the United States'is:

Y l. A method of making shoes comprising the steps of `.providing an overlasted upper, Pfheating the overlasted `margin of the upper to develop -al heatvreservoirfapplyfing a coating of thermoplastic 'adhesive' to the heated overautomatie;conveyersand'sifnilarV machines may be used Hto' advantage in the.'- practice, of. my invention.. Y 'll'.also be .notedfrom the foregoingdesription no,.aplfpfrleciableV consumption of `time in the laSted'rnargin, applying additional heat to the exposed surface of the Vadhesive coating, said heatreservoir-'an'd additional heat cooperating to set up the adhesive, providing a solehaving acoating of adhesive, at llealstn one 5 ofthe two,V rceatiss. vfadhesive betngin anxactiv state, Y

and coaligning the sole lwith the over-lasted margin of the upper to bond them together.

2. A. method of making shoes including the steps of lasting an upper upon a last, heating the overlasted margin of the upper to develop a heat reservoir in said overlasted margin, applying heat conditionable adhesive to the surface of the heated overlasted margin, applying additional heat to the exposed surface of the adhesive before the heat of the reservoir is dissipated whereby said adhesive is rapidiy conditioned by the simultaneous action or the applied heat and the heat from said reservoir, and thereafter pressing a sole upon said overlasted margin.

3. A method of making shoes including the steps 0f providing a sole element, providing a lasted shoe element having an overlasted margin, heating one surface of one of said elements to develop a heat reservoir in said element, applying a coating of heat conditionable adhesive upon the heated surface, applying additional heat upon the exposed surface of the adhesive before the heat of the reservoir is dissipated whereby said adhesive is rapidly conditioned by the simultaneous action of the applied heat and the heat from said reservoir, and thereafter pressing the sole element on the overlasted margin.

References Cited in the tile of this patent UNTED STATES PATENTS 1,919,464 Daniels July 25, 1933 1,951,474 Eastman Mar. 20, 1934 1,967,337 Tetlow .uly 24, 1934 1,998,505 Johnson Apr. 23, 1935 2,294,481 Ryan Sept. 1, 1942 2,395,133 Mahoney et al Feb. 19, 1946 

